This invention relates generally to the hand-loading of cartridge shells and, in particular, to work performed on the shell as part of the hand-loading process.
As shown in FIG. 1, a cartridge shell 10 includes a cylindrical wall 11, a base 12 and a shell upper rim 14. A primer chamber 15 is formed in the shell base 12 as shown.
During the manufacture of handloader shells 10, a flash hole 16 is also formed, typically in a punch press operation into the brass shell. While the punch formation of the flash hole 16 is economical, it typically leaves irregular breakouts and burrs at the inner portion of the flash hole as indicated at numerals 18 and 19.
Since the aforementioned breakouts and burrs are not uniform from shell to shell, the flash hole exit orifice varies significantly. Such results in variations in the primer flame front from shot to shot causing inconsistent velocity pressure and consequent loss of accuracy.
It has been recognized by those of skill in the art that shell to shell uniformity of the flash hole is of critical importance in achieving the close shot groupings desired in handloader gun competitions. Accordingly, the uniforming of flash holes has been practiced for nearly twenty years.
In a typical handloader flash hole uniforming process, a hand-held cutter is inserted into the flash hole 16 and used to ream and deburr the flash hole. It is also known that it is desirable to chamfer the flash hole exit orifice to provide even pressures and velocities within the shell.
With such manual uniformer operations, however, variations in the flash hole size and shape from shell to shell inevitably occur since the handloader cannot be sure of the depth of insertion of the cutting tool.
While flash hole uniformer tools have been known in the art, they are typically useable only for a shell of a given height and a single tool cannot be used for the wide range of shell heights encountered.
Accordingly, it is an object of the present invention to provide a flash hole uniformer tool which has a depth gage formed around the cutting tool in such manner that a uniform cutter depth is always achieved.
It is a further object of the invention to provide a flash hole uniformer which includes a slidable centering cone formed thereon such that the cutting tool always enters and does work on the flash hole at the desired straight angle.
It is also an object of the invention to provide a flash hole uniformer tool in which a single tool may be utilized for all standard rifle and pistol shells.
It is still a further object of the invention to demonstrate a flash hole uniformer tool which may be economically manufactured and sold to those of skill in the handloader arts.
These and other objects and advantages of the invention will be appreciated by those of skill in the art in the specification which follows.